Robert Panowicz

Based on a combination of hexagonal honeycomb and re-entrant honeycomb cells, the concept of novel hybrid cell structures was developed. Experimental studies and numerical analyses of the behaviour of the analysed structures under in-plane compression in two compression directions were carried out. Explicit finite element analyses with an explicit integration scheme, incorporating plastic deformation and ductile damage evolution models, were employed to analyse the entire deformation process, including plastic and damage stages. Good agreement was obtained between the results of the numerical analyses and the experimental studies.

This article presents methods of planning unmanned aerial vehicle (UAV) missions in which individual platforms work together during the reconnaissance of objects located within a terrain. The planning problem concerns determining the flight routes of a swarm, where each UAV has the ability to recognize an object using a specific type of sensor. The experiments described in this article were carried out for drone formation; one drone works as a swarm information hub and exchanges information with the ground control station (GCS). Numerical models for mission planning are presented, which take into account the important constraints, simplifying the description of the mission without too much risk of losing the platforms. Several types of objective functions were used to optimize swarm flight paths. The mission models are presented in the form of mixed integer linear programming problems (MILPs). The experiments were carried out on a terrain model built on the basis of graph and network theory. The method of building a network on which the route plan of a drone swarm is determined is precisely presented. Particular attention was paid to the description of ways to minimize the size of the network on which the swarm mission is planned. The presented methods for building a terrain model allow for solving the optimization problem using integer programming tasks.

Elastomers are widely used in many industries. Their use requires thorough knowledge of their strength and stiffness parameters over a wide temperature range. However, determination of the parameters of such materials is still a challenge. Therefore, the paper presents research methodology allowing determination of the properties of rubber-like materials in a wide range of stretch and temperatures (from +50°C to −25°C) by using the example of styrene-butadiene rubber (SBR) and natural rubber (NR) elastomers. Additionally, two blends, chloroprene rubber/nitrile-butadiene rubber (CR/NBR) and NR/SBR blends, were also considered. Based on physical premises, a polynomial and Arruda–Boyce hyperelastic constitutive models parameters were determined using two different methods, namely curve-fitting and the successive response surface method.

The experience of recent military missions clearly shows the importance of protecting vehicles and the people they carry from mines and IEDs. This protection can be achieved in many ways, using both active and passive solutions. One of the most popular solutions is using energy deflectors, which, thanks to their appropriately selected shape, can dissipate the energy from the detonation of an explosive charge, thus reducing the blast wave loading on the protected structure. The article presents the research results on two innovative groups of deflectors—double-bend and semi-spherical, characterized by a better ability to disperse energy than traditionally used V-shaped deflectors. Several possible geometric shapes differing in critical dimensions were selected, and both experimental studies and numerical analyses were carried out. A ballistic pendulum was used to measure individual deflectors’ performances. The tests proved the tested solutions’ increased effectiveness compared with V-shaped deflectors.

The paper presents an elemental description and methodology of tests that take intoaccount the effect of high strain rate on materials strength parameters. The article describes suchtesting methodology as: Taylor test, split Hopkinson pressure bar method, and expanding ring test todetermine the dynamic properties of materials.Keywords: Taylor test, expanding ring test, split Hopkinson pressure bar, dynamic behaviour of materials

The influence of the thermo-oxidative aging semi-crystalline polyethylene terephthalate process on the thermal and mechanical properties was analysed in the article. For this purpose, PET was aged at 140 °C for 21, 35 and 56 days. The research showed that as a result of aging, the amount of the crystalline phase increases by about 8%, which translates into the properties of the aged material. The glass transition and melt temperature of lamellar crystals formed during first and second crystallisation increase with aging. The mechanical properties of the material were analysed in the temperature range of 25 to 75 °C. The tests were showing an increase in Young’s modulus and a decrease in elongation at the break as a result of aging. This phenomenon was particularly visible during tests at 75 °C and during the morphological observation of the fracture surface, where the fracture character of the material changes from ductile to brittle. In the case of the material aged for the longest time, the temperature has a negligible influence on the elongation at break.